<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<link rel="stylesheet" href="./4.css">
<body>
    <div class="container" id="demo">
        <h1>h1</h1>
        <p>p1</p>
        <div>div1</div>
        <p>p2</p>
        <p>p3</p>
        <div>div2</div>
    </div>
</body>
</html>